1 Sport Fishery Biodata Results


1.1 Assumptions and caveats

Definitions of natural, hatchery and unknown origin Chinook:

  • A fish is assumed Natural origin if an otolith is returned as “Not Marked” and the adipose fin is intact. PBT is not currently considered as it is stock/facility-specific, and would likely only apply to very recent RYs (2022/2023).
    • This assumption may not be appropriate in cases where hatchery fish are not thermally marked AND have no other identifier (probably rare? Perhaps US?).
    • Intact adipose fins alone are NOT evidence of a natural fish, and are considered “Unknown” origin unless accompanied by more data
  • A fish is Hatchery origin if it has an adipose clip, a thermal mark, a CWT, and/or a PBT BY assignment (in recent years).
    • Note there are some rare cases of CWT wild-tagging programs in Yukon/Alaska, but these are not expected to show up in great numbers for Chinook.
  • A fish is Unknown origin if it has an intact adipose and no other mark or tag to inform further, e.g., destroyed or missing otolith, missing or lost tag, no samples analyzed, etc.)
  • Stock ID is assigned in order of reliability: CWT > PBT > Otolith > GSI. This is determined in the CREST database but is currently under review (PBT may shift to be more reliable).


The following caveats/assumptions must be taken into consideration when interpreting the recreational fishery data presented below:

  • A genetic stock ID is only included if it has >= 75% certainty.
  • It is assumed that biosampling is representative of kept catch, but this varies year to year as sample sizes are low.
  • Biosamples represent kept, legal catch and therefore do not represent the portions of populations <45cm or >80cm
    • Only legal sized Chinook are included here (> 45cm). Extra-legal (aka Super-legal) Chinook (>80cm) have also been excluded as current regs exclude these fish from the fishery.
  • No corrections are done to account for thermal mark issues from any facility in any given year. Missing thermal marks would show up as “Not Marked” and bias results towards reporting more natural-origin Chinook than may in fact exist.
  • Limimted GSI sampling in earlier years
  • Considerable changes to the recreational fishery along SWVI came into effect around 2018-2019 so comparisons across these years should be careful.
  • Unknown stock IDs were excluded from the following analyses. Results are expressed as regional population IDs as a proportion of known samples.


Please keep in mind sample rates for these areas are below ideal levels, so conclusions drawn should be very careful. Please read the last section that lays out the sample rates (i.e., % of kept catch sampled) by month and year!“



1.2 WCVI: Nitinat catch across all WCVI PFMAs (27-20 and offshore)

Proportion of legal sized biosamples that return as Nitinat in each Area applied to kept, legal catch estimates for 2017-2023 (note 2023 biodata still incomplete).


1.2.1 All Nitinat-origin across WCVI (hatchery + natural)

Applying stock comp %s from creel biosamples to estimated catch by Month/Area/Year. Note 2023 and 2024 are incomplete as of January 2025.

Figure 1.1: Kept catch estimates of legal size (>45cm and <=80cm) Nitinat-origin Chinook across WCVI PFMAs, organized from north (PFMA 127) to south (PFMA 20). Estimates calculated by applying the proportion of Nitinat chinook detected in creel biosamples to total year-month-area catch estimates. Interactive plot; hover over data points on heat map to see sample sizes and catch estimates. NOTE 2023 and 2024 samples are incomplete as of January 2025.



1.2.2 Hatchery Nitinat across WCVI


1.2.2.1 2023 Catch estimate map

Kept catch estimates of legal sized (>45cm and <=80cm) Nitinat Hatchery Chinook across WCVI in 2023. Estimates calculated by applying the proportion of Nitinat chinook detected in creel biosamples to total year-month-area catch estimates. **NOTE 2023 and 2024 samples are incomplete as of January 2025.**

Figure 1.2: Kept catch estimates of legal sized (>45cm and <=80cm) Nitinat Hatchery Chinook across WCVI in 2023. Estimates calculated by applying the proportion of Nitinat chinook detected in creel biosamples to total year-month-area catch estimates. NOTE 2023 and 2024 samples are incomplete as of January 2025.


1.2.2.2 2022 Catch estimate map

Kept catch estimates of legal sized (>45cm and <=80cm) Nitinat Hatchery Chinook across WCVI in 2022. Estimates calculated by applying the proportion of Nitinat chinook detected in creel biosamples to total year-month-area catch estimates.

Figure 1.3: Kept catch estimates of legal sized (>45cm and <=80cm) Nitinat Hatchery Chinook across WCVI in 2022. Estimates calculated by applying the proportion of Nitinat chinook detected in creel biosamples to total year-month-area catch estimates.


1.2.2.3 2021 Catch estimate map

Kept catch estimates of legal sized (>45cm and <=80cm) Nitinat Hatchery Chinook across WCVI in 2021. Estimates calculated by applying the proportion of Nitinat chinook detected in creel biosamples to total year-month-area catch estimates.

Figure 1.4: Kept catch estimates of legal sized (>45cm and <=80cm) Nitinat Hatchery Chinook across WCVI in 2021. Estimates calculated by applying the proportion of Nitinat chinook detected in creel biosamples to total year-month-area catch estimates.


1.2.2.4 2020 Catch estimate map

Kept catch estimates of legal sized (>45cm and <=80cm) Nitinat Hatchery Chinook across WCVI in 2020. Estimates calculated by applying the proportion of Nitinat chinook detected in creel biosamples to total year-month-area catch estimates.

Figure 1.5: Kept catch estimates of legal sized (>45cm and <=80cm) Nitinat Hatchery Chinook across WCVI in 2020. Estimates calculated by applying the proportion of Nitinat chinook detected in creel biosamples to total year-month-area catch estimates.



1.3 Area 21/121 catch composition

Figure 1.6: Estimated kept, legal (<45cm, >80cm) Chinook catch in Area 21. ID is to the Region-level in all cases except for Nitinat River. Estimates calculated by applying the proportion of Nitinat chinook detected in creel biosamples to total year-month-area catch estimates. NOTE 2023 and 2024 samples in incomplete as of January 2025.



Figure 1.7: Estimated kept, legal (<45cm, >80cm) Chinook catch in Area 121. ID is to the Region-level in all cases except for Nitinat River. Estimates calculated by applying the proportion of Nitinat chinook detected in creel biosamples to total year-month-area catch estimates. NOTE 2023 and 2024 samples in incomplete as of January 2025.



1.4 Sample rate

Sample rate is simply the number of samples collected divided by the estimated kept catch, calculated for each month/area/year. It can give an indication of sampling effort to interpret catch trends.

Sample rate or "sampling effort" of kept legal Chinook catch in all WCVI areas from 2017-2024. Sampling rate or effort is defined as the number of legal-sized biological samples collected in each area-month-year divded by the total kept legal catch estimate for that area-month-year. Catch estimates are point estimates; this does not take into account uncertainty around catch estimates.

Figure 1.8: Sample rate or “sampling effort” of kept legal Chinook catch in all WCVI areas from 2017-2024. Sampling rate or effort is defined as the number of legal-sized biological samples collected in each area-month-year divded by the total kept legal catch estimate for that area-month-year. Catch estimates are point estimates; this does not take into account uncertainty around catch estimates.